Help with Podcasting?

Hi.

I've been playing around with my blog (iBlog and Blogger), iPodder, and GarageBand in the hopes of creating a podcast. But I just can't get it.

Here's what I've done:
1) I created an .xml file based on the instructions in the February 2005 edition of MacAddict.
2) I created a song in GarageBand and converted it to an .mp3 file.
3) I put both files on my iDisk.
4) I put the URL of my public folder (containing the files) into iPodder as a new feed. (i.e. idisk.mac.com/myusername/public/myfeed.xml)
5) iPodder actually recognizes it and downloads my "episode" but the file size is listed as -0.0 MB. It even opened iTunes to play the file but there was no mp3 in the playlist.

Please, can someone point out what I'm doing wrong? I feel like I'm so close to getting this thing working despite being as novice as they come.

Thanks,

Squire